(1) The Field of the Invention
This invention relates to processing apparatus and methods. More precisely, this invention relates to rotary processors having improved sealing between processor regions at significantly different pressures.
(2) Description of the Prior Art
Rotary processors are known to the art. Details relating to such processors are described in U.S. Pat. Nos. 4,142,805; 4,194,841; 4,207,004; 4,213,709; 4,227,816; 4,255,059; 4,289,319; 4,300,842; 4,329,065; 4,389,119; 4,402,616; 4,411,532; 4,413,913 and 4,421,412.
Essential elements of the basic individual processing passage of rotary processors disclosed in the above Patents comprise a rotatable element carrying at least one processing channel and a stationary element providing a coaxial closure surface operationally arranged to form with the channel an enclosed processing passage. The stationary element has an inlet for feeding material to the passage and an outlet for discharge of material from the passage. A member providing a material blocking and material collecting end wall surface is also associated with the stationary element and arranged near the outlet. The end wall surface is adapted to block movement of material fed to the passage and to coact with the moving channel walls to establish relative movement between the blocked material and the moving channel walls. This coaction permits material in contact with the moving walls to be dragged forward to the end wall surface for collection and/or controlled processing and/or discharge.
As disclosed in the above Patents, the processing passages present a highly versatile processing capability. The passages are adaptable for performing such processing operations as melting, mixing, pressurizing, pumping, devolatilizing and homogenizing, among others, as well as adding ingredients to or withdrawing ingredients from materials processed in the passage.
U.S. Pat. Nos. 4,227,816; 4,213,709; 4,389,119; 4,402,616 and 4,411,532 relate to multi-stage rotary processors which include a plurality of processing stages, each having one or more processing passages. Material transfer passages or grooves are formed in the closure surface of the stationary element and arranged to transfer material from a passage (or passages) of one stage to a passage (or passages) of another stage.
U.S. Pat. Nos. 4,329,065 and 4,413,913 relate to apparatus and method, respectively, for devolatilizing materials. In accordance with the apparatus and method disclosed therein, viscous material is fed to the processing passage and, near the inlet, the material is collected at a spreading element and is spread as thin films on the sides of the rotating channel walls. A void space is provided downstream of the spreader and a port is provided communicating with the void space so that volatile materials can be withdrawn from the surfaces of the thin films carried past the void space. The thin films are carried forward through the passage toward the material collecting end wall surface where the films are scraped from the walls and collected for discharge.
U.S. Pat. Nos. 4,207,004; 4,289,319 and 4,300,842 relate to novel seals for controlling the leakage of viscous liquid material between closely spaced apart relatively moving coaxial annular surfaces, particularly those of rotary processors. U.S. Pat. No. 4,207,004 discloses an annular pumping channel on one of the surfaces and an annular liquid retaining channel on the other surface which cooperate to resist the flow of viscous leakage liquid. U.S. Pat. No. 4,289,319 discloses a seal including nested, truncated conical members of thin, stiffly-resilient material interposed in sealing relation between the surfaces. U.S. Pat. No. 4,300,842 discloses a plurality of helical channels on one of the surfaces to resist the flow of leakage liquid between the surfaces. However, none of the above Patents addresses the problem of providing effective sealing to prevent leakage of non-viscous, e.g. gaseous, material (pressure leakage) between passages of a rotary processor which are maintained at significantly different pressure levels, such as by drawing a vacuum in one of the passages.
This invention is directed to improved rotary processors having a novel configuration which provides special advantages in terms of sealing between processing passages which are maintained at significantly different pressure levels.